The present invention relates generally to stacking apparatus and more specifically to such apparatus which is designed to receive flexible formed polymeric articles from forming means and to stack such articles in nested relationship with each such stack containing a predetermined number of the formed articles.
In packaging of various types of articles such as for example cookies, candies, and other various food products, it has become customary to utilize relatively thin, lightweight polymeric trays formed with a plurality of cavities into which the articles are placed either individually or in groups. These polymeric trays offer a relatively lightweight means by which the articles can be both maintained in the desired orientation and protected from damage during subsequent shipment and handling thereof.
These polymeric trays are generally formed from sheet material by use of a thermal vacuum forming operation. Typically the dies used in such forming machines will be provided with a plurality of cavities whereby a relatively large number of such trays may be substantially simultaneously formed during a single cycle of the forming apparatus. These thus formed articles are then moved outwardly from the forming machine and through a stripper operation wherein the interconnecting web remaining from the sheet material is stripped from the respective containers and the thus formed containers are ready for final packaging and shipment to the ultimate user thereof. Because the dies used in forming the polymeric trays contain a plurality of cavities, each cycle of the machine results in the discharge of a relatively large number of such articles which typically will be arranged in a plurality of substantially parallel rows with each row containing a plurality of trays.
Once the formed trays have been stripped from the interconnecting web, they must then be stacked in nested relationship and packaged for shipment to the ultimate customer. Previously it has been necessary to employ hand labor in order to stack and package accurate quantities of the thus formed trays for shipment to the customer. However, the use of manual labor for this operation is both relatively inefficient and costly. Accordingly, it has long been desired to develop automated apparatus which may accurately count and stack the formed trays so as to reduce the amount of manual labor required in this final packaging operation. However, while various attempts have been made to accomplish this objective, none have resulted in a completely satisfactory apparatus for performing this task in a rapid, efficient and cost effective manner.
It should also be noted that because of the wide variety of sizes and shapes of these polymeric trays being manufactured, it is necessary that any such stacking apparatus, in order to be truly cost effective, must be capable of being readily adjusted so as to handle such articles differing in both width and/or length. Further, it should be noted that the individual trays within each row are provided with varying positioned (from one tray to the next in each row) lugs or protrusions to limit the nesting movement thereof and to facilitate subsequent unstacking during filling. Hence, it is necessary that trays in each tray within a row be stacked in sequence in order to avoid possible nesting alignment of these protrusions. Additionally, because of the speed with which the forming operation is being accomplished and the nature of the polymeric trays themselves, it is often difficult to assure that a tray will be properly located for each and every row during each stacking cycle. Thus, it is highly desirable that any such stacking apparatus employ individual means for accurately counting the trays supplied to each individual stack and releasing the stack for final packaging upon accumulation of the desired predetermined number.
The present invention provides an improved stacking apparatus which accomplishes these varied and often conflicting objectives. The stacking apparatus of the present invention employs a plurality of panels which are designed to be positioned in side-by-side relationship and incorporate within each panel individually operable elevator means which operate to receive the respective formed articles and to raise the articles into a nested stacked relationship with previously received articles. Each of the respective panel members is also provided with exit gate means which are designed to be individually controlled in response to appropriate signals from counting means and to release the stacked articles upon accumulation of the desired predetermined number of articles therein. Suitable infeed guide means are also provided which incorporate readily adjustable elongated rail members which are designed to be easily and readily positioned in substantially any desired spaced relationship so as to thereby assure that a wide variety of differently sized articles may be easily handled. Further, the panel members incorporating the elevator members are also designed to be easily removed and reinstalled in different positions so as to enable quick and easy alteration of the apparatus for handling of different sized containers. Thus, the stacking apparatus of the present invention offers the ability to accommodate the wide and varied sizes of formed articles which may be fed thereto while also offering the ability to be easily and readily converted from one size to another thereby minimizing the amount of time required to accomplish the changeover.
Additional advantages and features of the present invention will become apparent from the subsequent description and the appended claims taken in conjunction with the accompanying drawings.